33/12-2

General

Well 33/12-2 was drilled in the Tampen Spur area as one of the first wells in the Statfjord Field area. Primary target of the well was the Early Jurassic Statfjord Group, which was known to be productive in Brent Field located about 20 km to the southwest in the U.K. offshore. The Statfjord Formation was water wet in the 33/12-1 and 33/9-1 tests. The 33/12-2 wildcat was located to encounter the Statfjord Formation approximately 200 m high to the 33/12-1 well. The Middle Jurassic Brent Formation was prognosed to be erosionally thin or absent. Triassic, Permian and Devonian reservoirs were secondary targets. Planned total depth was 4572 m (15000 ft.), believed to be sufficient to reach Devonian age rocks or "Petroleum Basement". The well was one of the three deep tests called for by the License 037 work obligation.

The well is type well for the Alke and Lunde formations of the Hegre Group and the Raude and Eiriksson formations of the Statfjord Group. It is reference well for the Nansen Formation.

Operations and results

Wildcat well 33/12-2 was spudded with the semi-submersible installation Nordskald on 6 June 1974. Drilling proceeded to 4354 m in Early Triassic sediments of the Lomvi Formation. At this depth the drill string twisted off leaving a fish with top at 4157 m. Attempts to remove the fish were unsuccessful so 4354 m became TD of the well. No wire line logs were run below 4145 m. The well was drilled with water-based mud. Below 2716 m the mud contained from 2% to 8% oil.

As predicted, the Middle Jurassic Brent Group was thin (17.5 m) and oil bearing (12 m net). Test data and log correlation indicated that the upper reservoir in the 33/12-2 well is a sectio